introduction to java ee (j2ee). cse, iitb umesh bellur session objectives understanding the value...

Introduction toJava EE (J2EE)

Umesh Bellur

CSE, IITB

Session Objectives Understanding the value propositions of

J2EE Getting a big picture of J2EE architecture and

platform Getting high-level exposure of APIs and

Technologies that constitute J2EE You don't have to understand all the details

Understanding why J2EE can be used for as a platform for development and deployment of web services

Umesh Bellur

CSE, IITB

What is J2EE?

Umesh Bellur

CSE, IITB

ChallengesPortabilityDiverse EnvironmentsTime-to-marketCore CompetenceAssemblyIntegration

Key Technologies

J2SE™

J2EE™

JMS

Servlet

JSP

Connector

XML

Data Binding

XSLT

Products

App Servers

Web Servers

Components

Databases

Object to DB tools

LegacySystems

Databases

TP Monitors

EIS Systems

Enterprise Computing

Umesh Bellur

CSE, IITB

What Is the J2EE? Open and standard based platform for

developing, deploying and managing n-tier, Web-enabled, server-centric, and

component-based enterprise applications

Umesh Bellur

CSE, IITB

The Java™ Platform

High-EndServer

Java Technology Enabled Desktop

WorkgroupServer

Java Technology Enabled Devices

The JavaTM Platform

OptionalPackages

Java 2Enterprise

Edition(J2EE)

Java 2StandardEdition(J2SE)

JVM

Java Card APIs

CardVM

OptionalPackages

Personal Basis Profile

Personal Profile

Foundation Profile

CDC

MIDP

CLDC

KVM

Java 2 Platform Micro Edition(J2METM)

* Under development in JCP

Umesh Bellur

CSE, IITB

Open and Standard Solution Use "component and container" model in

which container provides system services in a well-defined and as industry standard

J2EE is that standard that also provides portability of code because it is based on Java technology and standard-based Java programming APIs

Umesh Bellur

CSE, IITB

Why J2EE?

Umesh Bellur

CSE, IITB

Platform Value to Developers

Can use any J2EE implementation for development and deployment Use production-quality standard implementation which is

free for development/deployment Use high-end commercial J2EE products for scalability and

fault-tolerance

Vast amount of J2EE community resources Many J2EE related books, articles, tutorials, quality code

you can use, best practice guidelines, design patterns etc.

Can use off-the-shelf 3rd-party business components

Umesh Bellur

CSE, IITB

Platform Value to Vendors Vendors work together on specifications and

then compete in implementations In the areas of Scalability, Performance,

Reliability, Availability, Management and development tools, and so on

Freedom to innovate while maintaining the portability of applications

Do not have create/maintain their own proprietary APIs

Umesh Bellur

CSE, IITB

Platform Value to Business Customers Application portability Many implementation choices are possible

based on various requirements Price (free to high-end), scalability (single CPU to

clustered model), reliability, performance, tools, and more

Best of breed of applications and platforms Large developer pool

Umesh Bellur

CSE, IITB

J2EE APIs &Technologies

Umesh Bellur

CSE, IITB

J2EE 1.4 APIs and Technologies J2SE 1.4 (improved) JAX-RPC (new) Web Service for J2EE J2EE Management J2EE Deployment JMX 1.1 JMS 1.1 JTA 1.0

Servlet 2.4 JSP 2.0 EJB 2.1 JAXR Connector 1.5 JACC JAXP 1.2 JavaMail 1.3 JAF 1.0

Umesh Bellur

CSE, IITB

Java EE 5 JAX-WS 2.0 & JSR 181 Java Persistence EJB 3.0 JAXB 2.0 JavaSever Faces 1.2 – new to Platform JSP 2.1 – Unification w/ JSF 1.2 StAX – Pull Parser – new to Platform

Umesh Bellur

CSE, IITB

Servlet & JSP (JavaServer

Pages)

Umesh Bellur

CSE, IITB

What is a Servlet? Java™ objects which extend the functionality

of a HTTP server Dynamic contents generation Better alternative to CGI, NSAPI, ISAPI, etc.

Efficient Platform and server independent Session management Java-based

Umesh Bellur

CSE, IITB

Servlet vs. CGI

CGIBased

Webserver

CGIBased

Webserver

Request CGI1Child for CGI1

CGIBased

Webserver

Servlet Based Webserver

JVM

Request CGI1Child for CGI1

Request Servlet1

CGIBased

Webserver

Servlet Based Webserver

JVMServlet1

Request CGI1Child for CGI1

Request CGI2

Request Servlet1

CGIBased

WebserverChild for CGI2

Servlet Based Webserver

JVMServlet1

Request CGI1Child for CGI1

Request CGI2

Request Servlet1

Request Servlet2

CGIBased

WebserverChild for CGI2

Servlet Based Webserver

JVMServlet1

Servlet2

Request CGI1Child for CGI1

Request CGI2

Request CGI1

Request Servlet1

Request Servlet2

CGIBased

WebserverChild for CGI2

Child for CGI1

Servlet Based Webserver

JVMServlet1

Servlet2

Request CGI1Child for CGI1

Request CGI2

Request CGI1

Request Servlet1

Request Servlet2

Request Servlet1

CGIBased

WebserverChild for CGI2

Child for CGI1

Servlet Based Webserver

JVMServlet1

Servlet2

Request CGI1Child for CGI1

Umesh Bellur

CSE, IITB

What is JSP Technology? Enables separation of business logic

from presentation Presentation is in the form of HTML or

XML/XSLT Business logic is implemented as Java Beans

or custom tags Better maintainability, reusability

Extensible via custom tags Builds on Servlet technology

Umesh Bellur

CSE, IITB

EJB(Enterprise Java

Beans)

Umesh Bellur

CSE, IITB

What is EJB Technology? A server-side component technology Easy development and deployment of Java

technology-based application that are: Transactional, distributed, multi-tier, portable,

scalable, secure, …

Umesh Bellur

CSE, IITB

Why EJB Technology?● Leverages the benefits of component-model

on the server side● Separates business logic from system code

Container provides system services● Provides framework for portable components

Over different J2EE-compliant servers Over different operational environments

● Enables deployment-time configuration Deployment descriptor

Umesh Bellur

CSE, IITB

EJB Architecture

Umesh Bellur

CSE, IITB

Enterprise JavaBeansEnterprise JavaBeans

Entity Bean Message-Driven Bean

Synchronous communication Asynchronous communication

Stateless Stateful

Bean managedPersistence

(BMP)

Container managedPersistence

(CMP)

Session Bean

Umesh Bellur

CSE, IITB

JMS(Java Message

Service)

Umesh Bellur

CSE, IITB

Java Message Service (JMS) Messaging systems (MOM) provide

De-coupled communication Asynchronous communication Plays a role of centralized post office

Benefits of Messaging systems Flexible, Reliable, Scalable communication

systems Point-to-Point, Publish and Subscribe JMS defines standard Java APIs to

messaging systems

Umesh Bellur

CSE, IITB

Connector Architecture

Umesh Bellur

CSE, IITB

Connector Architecture Defines standard API for integrating J2EE

technology with EIS systems CICS, SAP, PeopleSoft, etc.

Before Connector architecture, each App server has to provide an proprietary adaptor for each EIS system m (# of App servers) x n (# of EIS's) Adaptors

With Connector architecture, same adaptor works with all J2EE compliant containers 1 (common to all App servers) x n (# of EIS's) Adaptors

Umesh Bellur

CSE, IITB

m x n Problem Before Connector Architecture

AppServer1

AppServer

AppServer3

AppServer2

SAP

EIS4

EIS3

m n

EIS2

Umesh Bellur

CSE, IITB

JAAS (Part of J2SE 1.4)(Java Authentication &Authorization Service)

Umesh Bellur

CSE, IITB

JAAS: Authentication Pluggable authentication framework

Userid/password Smartcard Kerberos Biometric

Application portability regardless of authentication schemes underneath JAAS provides authentication scheme independent API Authentication schemes are specified Login configuration

file, which will be read by JAAS

Umesh Bellur

CSE, IITB

JAAS Pluggable Authentication

Umesh Bellur

CSE, IITB

Other J2EE APIs &Technologies

Umesh Bellur

CSE, IITB

JNDI Java Naming and Directory Interface

Utilized by J2EE applications to locate resources and objects in portable fashion Applications use symbolic names to find object

references to resources via JNDI The symbolic names and object references have

to be configured by system administrator when the application is deployed.

Umesh Bellur

CSE, IITB

JDBC

Provides standard Java programming API to relational database

Uses SQL

Vendors provide JDBC compliant driver which can be invoked via standard Java programming API

Umesh Bellur

CSE, IITB

J2EE Management (JSR-77) Management applications should be able to

discover and interpret the managed data of any J2EE platform

Single management platform can manage multiple J2EE servers from different vendors

Management protocol specifications ensure a uniform view by SNMP and WBEM management stations

Leverages JMX

Umesh Bellur

CSE, IITB

J2EE Deployment (JSR-88) - J2EE 1.4

Tools J2EE PlatformsStandard

Deployment API(Universal Remote)

IDEs

Vendor Deploy Tools

Management Tools

Umesh Bellur

CSE, IITB

J2EE App ServerApp

JMX

JMX

JMX defacto

Dynamic DeploymentJMX API into the J2EE 1.4 platform

A single technology for the J2EE platform

JMX

Umesh Bellur

CSE, IITB

J2EE is an End-to-EndArchitecture

Umesh Bellur

CSE, IITB

N-tier J2EE Architecture

Web Tier EJB Tier

Umesh Bellur

CSE, IITB

J2EE J2EE Component & ContainerComponent & Container

ArchitectureArchitecture

Umesh Bellur

CSE, IITB

JN

DI

J2SE

JM

S

RM

I/IIO

P

JD

BC

Database

AppClient

App Client Container

HTTP/HTTPS

J2SE

RMI

J2SE

JN

DI

JM

S

RM

I/IIO

P

JD

BC

JT

A JavaMail

JAF JN

DI

JM

S

RM

I/IIO

P

JD

BC

JT

A

JavaMail

JAF

HTTP/HTTPS

Applet Container

Applet JSP Servlet EJB

Web Container EJB Container

RMI

J2SE

J2EE Containers & Components

Umesh Bellur

CSE, IITB

ComponentsHandle

Concurrency Security Availability Scalability Persistence Transaction Life-cycle

management Management

Presentation Business Logic

ContainersHandle

Umesh Bellur

CSE, IITB

Containers & Components

Containers do their work invisibly– No complicated APIs

– They control by interposition

Containers implement J2EE– Look the same to components

– Vendors making the containers have great freedom to innovate

Umesh Bellur

CSE, IITB

J2EE ApplicationAnatomies

Umesh Bellur

CSE, IITB

DB & EISResources

Browser

Stand-alone

Web Server EJB Server

Web Server EJB Server

Possible J2EE Application Anatomies

Umesh Bellur

CSE, IITB

J2EE Application Anatomies● 4-tier J2EE applications

– HTML client, JSP/Servlets, EJB, JDBC/Connector

● 3-tier J2EE applications– HTML client, JSP/Servlets, JDBC

● 3-tier J2EE applications– EJB standalone applications, EJB,

JDBC/Connector

● B2B Enterprise applications– J2EE platform to J2EE platform through the

exchange of JMS or XML-based messages

Umesh Bellur

CSE, IITB

Which One to Use?● Depends on several factors

Requirements of applications Availability of EJB tier Availability of developer resource

Assignment 3

Umesh Bellur

CSE, IITB

Assignment 3 – Deadline Feb 5

Client(Browser)

JSP1 SB1

MDB SB2

JMS Topic

Booking server

Posting &Display server

Xaction. #

JSP2

Umesh Bellur

CSE, IITB

Notes on Assignment JSP 1 – takes in a a stock trade to do as input (Ticker

symbol & quantity) Assume all trades are buys. Invokes the SB

SB posts trade into a “Transactions” table (ID, Ticker symbol and trade amount) and the transaction ID (Unique) into the queue.

The MDB gets notified from the queue and invokes the SB2

SB2 reads the transaction and adjusts the “Positions” table. (Ticker symbol, Current position)

JSP2 is used to read the current positions. Build a delay into the MDB.